21851125 has 16 divisors (see below), whose sum is σ = 28154880. Its totient is φ = 16914000.

The previous prime is 21851119. The next prime is 21851153. The reversal of 21851125 is 52115812.

It is not a de Polignac number, because 21851125 - 2³ = 21851117 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (25).

It is a self number, because there is not a number n which added to its sum of digits gives 21851125.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1056 + ... + 6694.

It is an arithmetic number, because the mean of its divisors is an integer number (1759680).

Almost surely, 2^21851125 is an apocalyptic number.

21851125 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21851125 is a deficient number, since it is larger than the sum of its proper divisors (6303755).

21851125 is an equidigital number, since it uses as much as digits as its factorization.

21851125 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5685 (or 5675 counting only the distinct ones).

The product of its digits is 800, while the sum is 25.

The square root of 21851125 is about 4674.5186918013. The cubic root of 21851125 is about 279.5704510584.

Adding to 21851125 its reverse (52115812), we get a palindrome (73966937).

The spelling of 21851125 in words is "twenty-one million, eight hundred fifty-one thousand, one hundred twenty-five".